This invention relates to non-slip surface coatings.
The invention is primarily concerned with non-slip floor coatings for use in heavy industrial situations and was conceived in the context of off-shore oil platforms but it also has application in other situations and to decorative and prefabricated wall panels and to other decorative surface coatings.
There is a large demand for non-slip coatings especially in situations where slip can be imposed by adverse conditions despite the exercise of maximum care and when slip can be particularly hazardous. The situations that come to mind are, for example, on the surfaces of off-shore oil platforms where high winds and slippery water and oil soaked surfaces are common; on stairways and elevated walk-ways; and on pitching surfaces such as may arise on ships.
There are also many known proposals for non-slip coatings. For example GB No. 1,430,794 describes non-slip surfaces made by spreading a polymer-mineral mixture and providing roughness by mechanical means. This is suitable for roadways but is unlikely to provide the high non-slip standards required on oil platforms. GB No. 1,413,507 describes particles of aggregate precoated with bitumen, heated, and compacted followed by covering with fine aggregate wear-coated or sealed in bitumen. The disadvantage of such coatings are referred to below with reference to FIG. 1A. GB No. 1,222,655 refers to a non-slip coating of epoxy resin having carborundum grit embedded therein. The disadvantages of this type of coating is referred to below with reference to FIG. 1B. GB No. 1,107,193 describes methods of producing surfaces having a distinctly rough feel involving spraying a liquid medium containing granular solid substances. The problem stated here is that the liquid medium sprays preferentially to the solid substances and blockages occur. GB No. 886,375 mentions a floor covering having an upper layer comprising filler and binder. Whilst reference is made to non-slip properties it is unlikely that it would remain non-slip in the presence of oil as it has a nominally level trowelled surface.
A common process for generating heavy duty non-slip coatings involves blasting a base surface to clean and remove any loose material; treating with a primer to generate adhesion and set up corrosion protection; applying a binder by brush, spray, trowel or roller; and finally applying a non-slip aggregate or particulate material, generally by hand while the binder is tacky. Subsequent repair by over coating is not recommended.
This is a four stage process involving some degree of manual skill. The surface, when inspected closely, shows particles of non-slip material held rather in the manner of acorns in cups, the particles being the acorns and the set or cured binder forming the cups. This is generally satisfactory. The non-slip material, with its irregular shape, is exposed and held to provide a non-slip surface.
However, the hold between the particles and the binder can be broken with harsh use and one way of reducing this risk is to provide a protective sealer or wear coat. However, unless used very uniformly, the sealer can tend to smooth the surface and acts against the required non-slip quality. Another deterioration which can arise in this known process, in the absence of a sealer or wearcoat, is fracture of the exposed aggregate which then tends to fill in the cavities between the aggregate and hence smooth the surface. Further, such a surface is difficult to clean and could not be accepted where there is a risk of spillages of toxic material which need to be cleaned up. Similarly, it cannot be readily cleaned of oil spillages. Thus, in many situations, the use of a sealer becomes essential and the consequent loss of non-slip quality must be accepted.